The present invention relates to a method of controlling a set point of an electronic apparatus in accordance with one of a plurality of switch conditions.
Electronic apparatus with processing units such as microprocessors (.mu.Ps) are increasingly popular. In the electronic apparatus, keyboards are widely used for controlling various kind of set points. One method of setting the various set points (values) is to push a desired key selected from a key matrix. Another method is to keep pushing a predetermined key for increasing or decreasing sequentially a number (set point), and to release the key when the number is set to a desired value. However, rotary switches or slide switches are easy to operate by comparison with the keyboards in electronic measurement instruments such as oscilloscopes and waveform memory apparatus (digital storage oscilloscopes). In conventional methods of controlling set points with the rotary switches and slide switches, each switch contact corresponds to each set point, or each combination of a plurality of switch contacts corresponds to each set point. Assuming that a number of the switch contacts to N (positive integer) in the conventional methods, a number of the set points is only N when each contact corresponds to each set point, and the number thereof is 2.sup.N when each contact combination corresponds to each set point. Thus, a number of the switch contacts increases and the switches become complex and bulk as the number of the set points increases.